Potential of exhaust after treatment and engine technologies to meet future emissions limits

Report no. 99/62: In view of the European Auto Oil Process (AO2) a CONCAWE study reviewed literature (up to 9/1998) and in-house information on improved exhaust after treatment and engine technologies to reduce emissions from gasoline (stoichiometric, lean-burn,G-DI) and diesel vehicles (light and heavy duty).

Engine features include advances in engine combustion, fuel injection equipment, exhaust gas recirculation systems and management systems/strategies. The various technologies are summarised with regard to their application, advantages, disadvantages, fuel implications, fuel consumption and their likelihood to emerge on the European market.Based on the knowledge available at the time of the study, CONCAWE's experts assessed the potential of different technologies to contribute to meeting the year 2005emissions limits.

While it is concluded that vehicle technologies already exist to meet such limits even with current fuel quality, for conventional gasoline vehicles, no current light duty diesel vehicle achieves these limits. For light and heavy duty diesel vehicles, several technologies exist (traps, de-NOx) which will be further developed,and fuel quality will depend on the conversion efficiency and durability needs of such catalyst technology to meet 2005 limits and beyond. The SCR (urea de-NOx) system would be expected to be sulphur tolerant and applicable for heavy duty engines.Continuous regenerative traps (CRT) should operate satisfactorily with the 2005sulphur level (50 mg/kg).

De-NOx catalyst systems required for gasoline direct injection systems (G-DI) are under rapid development and improvements in their sulphur tolerance could be expected. In the Fuels Directive 98/70/EC fuel sulphur has been specified to enable new technologies to meet future emission limits.